A hull is the watertight body of a vessel such as a ship or a boat. The structure of the hull varies depending on the vessel type. Functionally, vessel hulls can be divided into two categories: planing and displacement. When a person purchases a vessel, the main design consideration is usually dictated by where and how the vessel will be used.
The difference between the two is where the vessel rides in the water when under moderate to maximum power. A displacement hull rides in the water, supported exclusively or predominantly by buoyancy. A displacement hull is not designed for high speed but rather travels through the water at a limited rate, which is defined by the waterline. They are often heavier than planing types, though not always. For example, many sailboats, shrimp boats, or tankers have a displacement hull.
A planing type hull rides on the water such a ski boat, race boat and most “sport fishing boats.” The planing hull form is configured to develop positive dynamic pressure so that its draft decreases with increasing speed. The dynamic lift reduces the wetted surface and therefore also the drag. Planing hulls are more efficient at higher speeds, although they still require more energy to achieve these speeds. Planing hull design configurations include those generally referred to as a flat bottom, a Vee-(or V-)bottom, tunnel or V-tunnel hulls.
Flat bottom vessels have the least draft and adapt well to floating in very shallow water. However the flat bottom design becomes very uncomfortable when the vessel is planing in rough water. A vessel of the vee-hull design (or V-hull) offers a more comfortable ride in rough water because it can cut through the waves. However, when at rest, the V-hull configuration requires more draft and is less stabile, pitching and rolling more than any other hull design. Vessels of the tunnel hull design have a longitudinal channel under the hull. The purpose of this channel can be to entrap air and compress it to cushion the ride in rough water or allow the motor and propeller to be raised so the vessel can be operated in shallow water. However, the tunnel hull has some of the disadvantages of the flat bottom designs, such as an uncomfortable ride in rough water. Whenever a person buys a planing hull vessel, a decision must be made as to which hull design would be the most advantageous for the conditions usually encountered when operating the craft, choosing between stability at rest and the smoothest ride under power.
Planing vessels are often powered by one or more outboard motors that are aft-mounted, a single engine centrally positioned, or a pair of twin engines symmetrically placed aft. However, other motor positions are possible such as a recessed position. Another type of planing vessel is an airboat that is powered by topside motor that powers a powerful topside propeller that produces a rearward column of air that propels the airboat forward.
It is often desirable to have a design that is more adaptable to different boating situations. Vessels generally are manufactured with a fixed hull. Some add attachments on to the existing fixed hull structure and other fixed design modifications that are not contemporaneously adaptable. One proposal is to have hinged slats that can be repositioned by vacuum. Others have created a thick layer of air bubbles under the aft section to reduce drag without transforming the hull. Others allow for switching from outboard to airboat.
While these units may be suitable for the particular purpose employed, or for general use, they would not be as suitable for the purposes of the present disclosure as disclosed hereafter. Others lift the stern to change from displacement to planing mode. Most require that any changes to the hull must be made with the vessel out of the water.
In the present disclosure, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which the present disclosure is concerned.
While certain aspects of conventional technologies have been discussed to facilitate the present disclosure, no technical aspects are disclaimed and it is contemplated that the claims may encompass one or more of the conventional technical aspects discussed herein.